1. Field of the Invention
This invention relates to an environmental control system for a vehicle, and in a preferred aspect to a system for predicting internal misting (fogging) of a vehicle window, especially but not limited to a vehicle windscreen.
2. Prior Art
U.S. Pat. No. 6,422,062 describes an integral sensor unit for predicting misting of a vehicle windscreen. The unit comprises a windscreen temperature sensor assembly, an ambient second temperature sensor assembly and an ambient air humidity sensor assembly, all contained within a common dome-shaped housing. In use the housing is attached to the interior surface of the windscreen and is connected via a multi-conductor lead to a control unit located away from the housing, e.g. in the vehicle header.
A disadvantage of this unit is that its presence on the windscreen can be distracting to the driver and/or obscure his vision. Also, by placing the ambient air temperature and ambient humidity sensor assemblies in the same housing as the windscreen temperature sensor assembly they are necessarily enclosed near to the windscreen and hence may not be truly representative of the ambient temperature or atmosphere in the main passenger cabin of the vehicle. The presence of the unit and its cabling may also be aesthetically unattractive.
It is an object of the invention to provide an environmental control system for a vehicle, and especially but not limited to an improved system for predicting internal misting of a vehicle windscreen or other window which avoids or mitigates these disadvantages.